Bearing



Patented July 4, 1933 UNITEDSTATESIPATENT o F- cr.

CHARLES E. SHERWOOD, OF HIGHLAND PARK, MICHIGAN, ASSIGNOR T SHERWOOD .PATENTS, LTD., 01' SAN FRANCISCO, CALIFORNIA, A CORPORATION OF CALIFORNIA BEARING No Drawing.

-' tion of which is copper and tin.

Another object of m invention is to produce sucha structure y sintering the powdered metal from which it is formed in a reguclilng bath-as for. instance, in a cyanide While various metals and combinationsof metals may be advantageously-used, depend cut to some extent upon the work which is to be performed by the finished product, I have secured excellent results in various types of bearings fabricated largely of powdered copper and tin. In such a structure, I prefer to use a small proportion of graphite as well as a small proportion of other lubricant, the latter constituent serving not only toassist in bonding the materials together prior to sintering, but also to assist in flowing the constituents into the mold. I have used powdered copper in proportions of from 75 to 95%, powdered tin in proportions of from 5 to 20%, graphite up to 2% and lubricant from .2 to 5%, all h weight. The constituents may be thoroug y mixed together,

poured into a mold and compressed to form a briquette of the desired shape. The pressure to which the mixture is subjected may be varied to suit conditions. pressure I have found' is approximately 30,000 pounds per square inch. The pressure, however, may vary from 10,000 pounds perhsquare inch to 75,000 pounds per square inc it may be sintered in a reducing bath. One very desirable bath is a molten cyanide bath.

.The heat to whichfthe briquette is subjected may be varied in accordance with. the metals used, it being advantageous to have the heat slightly-below the melting point of the metal im re at' One desirable p gn the cyanide remaining in t the bearing has been allowed'to dry, it may After the brlquette has been thus formed,

Application filed November 1a, 1929. Serial in. 407,020.

1500 Fahrenheit. If the metal used has a higher or lower melting point than copper, the heat may be varied accordingly.

The'lubricant-used in the mix may be ordinary lubricating oil which will volatilize appreciably below the sintering .tem rature with a resultant production of voi s in the sintered bearing.

I It will be readily apparent that the briquette to be formed may take any desired form or shape. For instance, a perfectly round bushing or hearing structure may be formed or the structure may be formed in sections and assembled, as in the case of main or connecting rod bearings for internal com bustion engines.

The bearings so formed will be highly p0- rous in structure and will oftentimes be capable of absorbing up to of their volume in pil. The bearin so formed and impregnated with oil mayfie used in many instances without continuously supplying lubricant thereto, inasmuch as the bearing is inherently self-lubricating.

- The reducing bath to which the bearing is subjected not only prevents oxidation of the minute particles which compose the hearing,

but also reduces any oxides that may be contained in'the briquette and the particles are coalesced, producing a much stronger structure than those which have oxides between metallic particles.

r sintering of the bearing and before the same with oil, it' is desirable that the bearmg be submerged in boiling water or the like for a period of 20 to 30. minutes, after which it is-rinsedin additional bo' water to remove as nearly be impregnated with lubricant.

as possible all o structure. After A bearing produced as herein described will possess the characteristics of bein strong and hard, as wellas porous and wi therefore, withstand much harder usage than will a bearing formed from similar metals which have not been sinteredin a reducing bath.

It will be obvious that various changes may be made in the materials used, the proportions thereof, in the bath to-which the bearing is subjected, as well as in many other details. I have herein described one form of my invention and method of making the same, .but donot wish to be limited to the specific hearing which comprises compressing powdered copper, powdered tin, graphite, and a volatilizable lubricant into a briquette, and immersing said briquette in a molten cyanide bath, said lubricant having a volatilizing temperature lower than the fusion temperature of the cyanide bath.

3. The method of forming a porous metal hearing which comprises compressing powdered-metal and a volatilizable substance into a briquette, and immersing said briquette in a molten cyanide bath.

CHARLES F. SHERWOOD. 

